Single-stage method of butadiene production

Abstract

The invention relates to a gas-phase synthesis of butadiene from ethanol or from a mixture of ethanol and acetaldehyde. The method of production includes conversion of ethanol or a mixture of ethanol with acetaldehyde in the presence of a catalyst, wherein the reaction is carried out in the presence of a solid catalyst with a mesoporous Zr-containing zeolite having a BEA type structure and at least one metal in a zero oxidation state selected from the group: silver, copper and gold. The claimed method is suitable for carrying out the reaction under continuous flow conditions in the reactor with a fixed bed of catalyst. The invention makes possible to achieve a high yield of butadiene with high selectivity to butadiene and high stability of the catalyst.

Description

FIELD OF THE INVENTION[0001]The invention belongs to the field of chemical industry and is intended for production of monomer-butadiene.BACKGROUND OF THE INVENTION[0002]Butadiene is used mainly as a monomer in the synthesis of synthetic rubbers like polybutadiene, butadiene-nitrile rubber, butadiene-styrene rubber, etc.[0003]Currently, there are two main methods to produce butadiene in industry. First is butadiene isolation from the products of pyrolysis of oil. Second represents butadiene synthesis via one- or two-stage catalytic dehydrogenation of normal butane and butenes of oil processing gases and associated gases. However, due to the rise in oil prices, technologies for production of butadiene from ethanol provoke interest.[0004]Historically, the first methods for production of butadiene from ethanol are processes consisting of two stages: the dehydrogenation of ethanol to acetaldehyde with the subsequent conversion of a mixture of acetaldehyde and ethanol to butadiene. Copper...

AI Technical Summary

Benefits of technology

[0017]The goal of the present invention is development of one-stage process for synthesis of butadiene from ethanol and mixtures of ethanol with acetaldehyde, over the catalyst capable for achieving high and stable butadiene yield along with high selectivity to butadiene over multiple synthesis-regeneration cycles.

[0024]Regeneration of the catalyst is possible at the temperature of 350-650° C. in an oxygen-containing gas stream with the repeated use of the catalyst for synthesis of butadiene while maintaining the initial activity, selectivity and durability parameters.

[0025]The result of the method in the scope of claim 1 is the high yield and selectivity to butadiene with high stability of the catalyst during the reaction and after regeneration.

[0026]This result is achieved by designing the catalysts with the structure that provides free access of the reagents and reaction products to the active sites and protects the outer surface of the zeolite crystals from accumulation of heavy products. Facilitation of the mass transfer of the molecules of reagents to the active sites of the zeolite located inside the zeolite channels and the mass transfer of the reaction products from the reaction zone gives a possibility to obtain high yields of the target product, butadiene. This leads to the decrease of formation of by-products and coke precursors and to an increase of the rate of regeneration with the coherent decrease of the regeneration temperature.

Problems solved by technology

However, due to the rise in oil prices, technologies for production of butadiene from ethanol provoke interest.

In this method, acetaldehyde required for the reaction is formed directly on the catalyst in situ, hence increasing the selectivity of the process and reducing the yield of undesirable by-products.

However, despite the large surface area of the support, this method has the same disadvantages as its prototype (RU 2440962).

Disadvantage of all the listed above methods utilizing oxide catalysts and supported oxide catalysts is a low yield of butadiene due to the use of bulk oxides and / or non-uniform distribution of active metals and oxides on the surface of the catalysts.

However, the small pore size of the zeolite material hinders desorption of the reaction products, as well as the coke precursors, leading to the fast deactivation of the catalyst.

The disadvantages of the known methods, including the prototype, are the low selectivity of the ethanol conversion towards butadiene due to the presence of strong acid sites that are responsible for the side reactions of ethanol dehydration to ethylene and diethyl ether, high regeneration temperature, rapid deactivation of the catalyst.

Moreover, the high price of metals and oxides used in the preparation of the catalyst requires high catalyst stability and long catalyst lifetime.